Mechanical and hydrodynamic homecare devices to clean rough implant surfaces - an in vitro polyspecies biofilm study.

OBJECTIVES: To investigate the cleaning efficacy of a mechanical and a hydrodynamic homecare device on biofilm-coated titanium surfaces with and without chlorhexidine. MATERIAL AND METHODS: Six-species biofilms were grown on 108 SLA-titanium discs, which were cleaned as follows: sonic toothbrush alone (i) or in combination with either a 0.2% chlorhexidine (ii) or a placebo gel (iii) and oral irrigator (hydrodynamic action) with water (iv) or combined with 0.2% chlorhexidine solution (v). Untreated samples served as control (vi). Biofilms were then harvested either immediately after treatment (study part A) or after a regrowth phase of 24 h (study part B) and colony-forming units (CFU) were assessed. Results were analysed using Whitney U-tests between the treatment groups. After the Bonferroni correction, the significance level was set at alpha = 0.0033. RESULTS: The median CFU counts directly after instrumentation accounted - in ascending order (P-values in comparison with the control group A6 were <0.001 for all groups except for A3: P = 0.014) - 2.0E1 (A5), 1.1E5 (A4), 3.6E5 (A2), 3.3E5 (A1) and 6.8E6 (A3), respectively. The untreated control group showed the highest CFU counts: 1.8E7 (A6). After regrowth, the following CFU counts were measured in ascending order (all P-values <0.001 when compared to the control group B6 = 2.0E8): 1.6E2 (B5), 1.9E5 (B2), 1.4E7 (B4), 3.1E7 (B1) and 3.9E7 (B3). CONCLUSIONS: An oral irrigator combined with 0.2% chlorhexidine is effective in reducing biofilms attached to rough titanium surfaces immediately after cleaning. Following a regrowth phase of 24 h, micro-organisms could be equally effective removed with a sonic toothbrush combined with 0.2% chlorhexidine and an oral irrigator with 0.2% chlorhexidine.